1. Field of the Invention
The present invention relates to a digital broadcasting receiver, and more particularly, to a digital broadcasting receiver, a driving method and a self-diagnosis method thereof that can diagnose and settle its problems by itself.
2. Discussion of the Related Art
In general, a digital broadcasting receiver can be roughly divided into three receiving methods.
First, there is a ground wave broadcasting receiving method, which includes a VSB (Vestigial Side Band) method and an OFDM (Orthogonal Frequency Division Multiplexing) method. Second, a cable broadcasting receiving method, which includes QAM (Quadrature Amplitude Modulation) method. Third, a satellite broadcasting receiving method, which includes QPSK (Quadrature Phase Shift Keying) method
These three receiving methods are different each other in their analog reception block, signal synchronization method, channel equalizing method, matched filter, and channel demodulation method.
However, recently, a multi-medium digital broadcasting receiver capable of incorporating the above-mentioned receiving methods is under development.
FIG. 1 is a block diagram illustrating a construction of a general multi-medium digital broadcasting receiver. As shown in FIG. 1, the general multi-medium digital broadcasting receiver includes: an analog reception block 101 for receiving a radio frequency (RF) signal and converting the signal into an intermediate frequency (IF) signal; a digital demodulation block 102 for demodulating a converted digital signal using an A/D (Analog/Digital) converter 101g. 
The analog reception block 101 receives a radio frequency signal of 50-860 MHz, converts the signal into an IF signal, converts the converted signal into a digital signal using an A/D converter 101g, and delivers the digital signal to the digital demodulation block 102.
The analog reception block 101 includes: a tuner 101b for converting a RF signal of 50-860 MHz received through an antenna 101a into a first IF signal of about 44 MHz; a surface acoustic wave (SAW) filter 101c for filtering a signal outputted from the tuner 101b; a first oscillator 101d for generating an oscillating frequency so as to generate a second IF signal; a mixer 101e for converting the filtered signal into a second IF signal by down-converting the signal filtered by the SAW filter 101c using an oscillating frequency generated at the first oscillator 101d; a second oscillator 101f for generating a sampling frequency; and the A/D converter 101g for converting a signal converted by the mixer 101e into a digital signal according to a sampling frequency generated at the second oscillator 101f. 
At this point, the analog reception block 101 among elements of the multi-medium digital broadcasting receiver has a standardized construction as shown in FIG. 1 regardless of demodulation methods.
On the contrary, the digital demodulation block 102 may have a variety of forms depending on demodulation methods such as VSB, OFDM, QAM, QPSK.
Generally, the digital demodulation block 102 may include a gain recovery, a phase splitter, a complex multiplier, an interpolator, a match filter, a symbol clock recovery, a channel equalizer, a carrier recovery, and an FEC (Forward Error Correction).
However, since the multi-medium digital broadcasting receiver is operated in response to an individual lock of each element, there is a problem in that stability of a system is deteriorated if a false lock is generated between the elements.
For example, if a gain recovery operates after a system is reset, other elements should be a reset mode.
However, with a gain of a received signal not tracked up to an appropriate level, if a channel equalizer of a blind state is operated, there is high possibility that the channel equalizer operates in its state of local minima. Such characteristics are fatal to system stability.
Further, since a training sequence does not exist in the QAM method, there is high possibility that a symbol clock recovery and a carrier recovery diverge.
Further, the symbol clock recovery operates in response to an automatic gain control (AGC) lock signal from a lock detector of the gain recovery.
However, the elements at the end should maintain a reset state constantly, but if the channel equalizer operates, there is high possibility that the channel equalizer operates in the state of local minima, which is fatal to system stability.